Switchboard



(No Model.) 3 Sheet-Sheet 1.

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Y SWITGHBOARD. No. 560,275. Patented May 19, 1896. Z1 2 'z2 Z5 QIIZ .1:1 31x ily? LC @L @i L; 7'61 g Jw gv W ZH@ 2- L 1f l. L. 12 2 ma n wg "f Q fill. 1I 1 f4/jf uf w45 mzni 6, \6/5 15 15 213i is@ 'L lw 14 LC/14. c55 #m 4, j j UI l jb zu 14x55 7u); n;

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lNo. 560,275. Patented May 19, 1896.

WITNESSES Y INVENTOH l @$31. MLM @j @Q7/LA D.M.MUNR0.

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SWITGHBOARD.

(No Model.)

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Patented May 19, 1896.

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INVEN FOR WITNESSES Y f" t ANDREW BLRAMAMJHUTDUTHQ WASNINGTUKIC.

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UNrrnD STATEs PATENT OFFICE,

DAVID M. MUNRO, or eAirHnRsBURe, MARYLAND.

sWlToHBoARD.

SPECIFICATION forming part of Letters Patent No. 560,275, dated May 19, 1896.

i Application iileflIebruary V26, 1896. Serial No. 580,786. (No model.)

T0 all wiz/pnt t ntay concern:

Beit known thatI, DAVID M. MUNRO, a citizen of the United States, residing at Gaithersburg, in the county of Montgomery and State of Maryland, have invented a new and useful Improvement in Switchboards, of which the following is a specification.

My invention relates to improvements in switchboards for the central stations of telephonie and telegraphic systems, the object of my invention being to provide a switchboard by means of which the dilerent subscribers lines can be connected in a more. convenient and speedy manner than with those at' present in general use. Y

The most common class of switchboards now used is that whereby the subscribers lines are electrically connected by means vof terminal plugs joined by a iexible conductrIhe objection to this arrangement is the great liability of the numerous cords to become broken by repeated bending. One ofA the objects of my invention is to dispense with these flexible cords and to provide means whereby any two subscribers circuits can be electrically connected or disconnected merely by sliding out or in a single switch-plug.

A further object of my invention is to provide a switchboard in which not only two subscribers lines, but three, four, or any number up to the entire series can be brought into a continuous circuit and the subscribers into mutual communication with each other.

A further object of my invention is to provide means whereby at the central station of a large exchange where several switchboards are required a subscribers line on any one switchboard can be rapidly and conveniently connected with any line on any other switchboard.

In the drawings, Figure I is a diagrammatic representation of the electrical connections of the switchboard as they appear when none of the subscribers circuits have been joined, while Fig. 2 is a similar diagram illustrating the connections when subscribers are brought into communication with each other. Fig. 3 is a perspective view of my improved switchboard, a portion being broken away to show a switch-plug and its contacts. Fig. 4 is a plan view, on an enlarged scale, of a portion of one of the shelves, showing more clearly the structure of the plug. Fig. 5 is a section of the same on the line 5 5, Fig. 4. Fig. Gis a perspective view of one of the plugs in the upper row detached. Fig. 7 is a similar view of one of the plugs in a lower row. Fig. Sis a rear view of the top board of the front wall of the switchboard, which is opposite to the top shelf thereof; and Fig. 9 is -a diagrammatic view of the connections for a multiple switchboard arranged according to my improved system.

Before describing the specific mechanism v ot my improved switchboard I will first ex- 'plain the principles embodied in its construction.

In the diagram, figures l l2 13 14 I represent metallic subscribers lines of a telephonic-exchange system, each circuit being brought into connection with the switchboard by two terminals y x2 y2, dac. I have selected five such lines as being a sufficient number to illustrate the nature of my invention; but it will be readily seen that the invention is equally applicable to any number of lines however large.

Each subscribers circuit is normally completed on the switchboard by a loop, as m/ n' m2 n2, dac., and in these loops are the usual annunciator-drops. Premisin g that in the diagram the thin lines represent permanent metallic lines or wires, while the thick short lines represent bridges or switch connections that may be broken, it will be observed that the irst portion m of each of said loops comprises a number of wire connections between contact-points alternated by bridges between said points, while the second or return portions n consist each of a single uninterrupted line-wire back to the terminals y.

Of the bridges in the portionsm of the loops it is to be observed that the first series p q p2 q 2, 85e., are to be broken when it is desired to include in any one of the subscribers lines the receiver, transmitter, and signaling instrument'of the attendant at the central station. To these instruments proceed two lines u t through contact-points r' s r2 S2,&c. ,which are adjacent to the pairs of contacts p q, the line uv passing through the points 0" adjacent to the points p, and fu passing through points s adjacent to q. In order to close the battery or primary circuit of the central-at- IOO tendants transmitter, there are also provided two lines ij, having bridges o o2, duc., which may be closed by a plug. If now any subseriber-as, for instance, No. 3-is communicating to the central station, the attendant thereat, being apprised of the fact by the corresponding annunciator-drop, will close the bridge o3 and will at the same time break the connection p3 Q3 and close psf/'3 (1333. rl`he central telephone will then be included in No. 3 circuit.

In addition to the contacts for including the instruments at the central telephone each loop-line m n, or, in particular, the portion m thereof, contains a series of pairs of contacts for connecting the subscribers line corresponding to that loop with the other lines of the system, there being as many pairs as there are remaining lines-in other words, the number of such pairs of contacts in each loop-lineis one less than the total number of subscribers. These bridges or pairs of contact-points are represented in the diagram by the letters a Z; or by the letters c CZ, the former being used to denote in any loop a bridge which must be broken to introduce a subscribers circuit of a higher number than the circuit of said loop, while the letters c (Z represent 4a bridge for introducing a circuit of a lower number than that of the loop. Thus the first loop m n contains the bridges @12h12 als Z)13 a Z214 n.15 Z115 for connecting with lines of higher numbers, while the loop m5 n contains the bridges c45 245 035 (P5 c25 CF c15 d15 for connecting with lines of lower numbers. These loops and the bridges therein are so disposed that the bridge a Z) for connecting with a line ol' a higher number is placed in proximity to the corresponding bridge c cl of the latter line for connecting' with the former line, as shownV in the diagram.

Now suppose it is required to connect N o. l subscriber with No. 3. All that is necessaryis to break the connections a Zisand c13 Z13 and join (L13 with c13 and Z113 dm. The completed circuit of the two lines thus joined is shown in Fig. 2.

An import-ant feature of my invention is that when two subscribers lines are connected each line is introduced into the other at two adjacent or successive points on the same wire of the latter and takes the place of a bridge in said line. From this it follows that not only two local lines, but three, four, or any number of the lines, can be brought into simultaneous communication with each other. This I have also illustrated in Fig. 2, where it is seen that line 4 is connected with line 2 at the points a2* C24 b2* (124, while line 5 is brought in'to the same circuit by connecting c25 c25 Z925 (Z252 It will readily be seen that with this system all the lines can be brought into the same circuit, it' desired.

I will now describe the specific apparat-us which I have devised for operating the foregoing system of exchanges.

My improved switchboard, as illustrated in Fig. 3, comprises a vertical series of horizontal shelves orboards 2, supported by side walls 3, the whole being formed into a suitable framework bya top it and base 5. Upon the top 4t of the switchboard are placed the terminals X Y of the subscribers circuits, in pairs. Upon the first shelf, which I call the attendants shelf, are arranged the contacts for switching the central-attendants in,- struments into any one of the subscribers circuits. This switching device for each circuit comprises, rst, a pair of spring-jacks I R, of which P is connected with the terminal X, while R is connected with a wire to the central instruments, as has been explained and illustrated diagrammatically in Fig. l; next, a pair of contact-plates Q S, located on the upper side of the telephone-shelf, underneath the spring ends of the jacks I) R, the circuits from the plates Q S being such as are shown in Fig. l in relation `to the points q s-that is, from Q the line proceeds to contact-points on the lower shelves and thence back to the other terminal of the subscribers circuit, while the line from S goes to the central telephone. Next there is provided a switch-plug T of insulating material, having at its front end, on its upper side, contactplates I R', which normally lie beneath and in contact with the ends of the spring-jacks P R, and on its lower side contact-plates Q if", which are normally in contact with the plates Q S. The plates I Q are connected through the plug, while the plates R S are insulated from each other. Thus in the normal position of the switclrplug the circuit is from the terminal X through spring-jack I, plate P, plate Q', plate Q, loop-line of the switchboard, (and other subscribers lines il' connected up,) and back to the terminals Y, as is illustrated in lines l 2 4 5 of Fig. 2, while the central-telephone circuit is cut out. Now on the rear end of the switch-plug are located bridge-plates*U on the upper surface and V on the lower surface-insulated from each other and of such dimensions as that when the switch-plug is pulled out or forward the bridge-plate V shall contact with the ends of both of the spring-jacks P R, while the plate V will bridge the plates Q S. The eiiect ol' this will be to throw the central telephone into the subscriber-s circuit, as illustrated in line 3 of Fig. 2, said telephone-line taking the place of the bridge P P Q Q, which will be broken.

Upon the rear surface of the front wall ol the switchboard illustrated in Fig. S are carried two lines I J to the battery or prilnary circuit of the central transmittinginstrument, normally open, but adapted to be closed across the wires I J by means oi' any one of the spring-plates O O2, circ., one end of each of which is permanently connected to the wire J, while the other endof any springplate, as O3, is broughtv into contact with the wire I when its switch-plug T is drawn forward, its end pressing against the plate O3 and causing IOO IIO

it to make contact with the wire I. Thus the same operation which throws the central instruments into the subscribers circuit will also close the primary circuit of the transmitter. The shelves below the rst support the switches and contacts for connecting the different subscribers circuits. In general the arrangement is similarv to the above-described devices for including the central telephone. Thus there are springjacks similar to the spring-jacks P R and contact-plates on the shelves similarto the contact-plates Q S. The switch-plugs E have bridge-plates F G like the bridges U V and upper and lower contactplates A C B D like the plates P' R Q' SQ with this sole difference, that while the plates R S were insulated from each other the plates C D are electrically connected through the insulating-plug. The circuits from these jacks and plates are such as are shown diagrammatically in Fig. l proceeding from the points CL Z) c d. It will now readilybe seen that while in the normal position of the switchplugs the circuits will be as shown in Fig. l, the effect of pulling out any plug so as to bring the upper and lower bridge-plates F G into operation will be to put two subscribers lines into communication with each other, as illustrated diagrammatically in Fig. 2.

To pull out the plugs, there are provided knobs or handles K, secured to the plugs by rods k, passing through apertures in the front wall G of the switchboard. The knobs II of any row are numbered in order, as 1, 2, {43,7} 4,77 LQC. (2,77 (3,97 4777 C5777 (KUCH, ((3,77 l, rbc., and they are similarly numbered in the columns. The knobs of the first row indi.- cate by their numbers that by pulling the knob of a certain number the central telephone will be included in the subscribers circuit of that number.

In the lower rows the number on a knob indicates that by pulling the knob the subscribers circuit of that number will be connected with thecircuit having the same number as the column in which the knob is situated.

The operation then is as follows: The central attendant, having been apprised by the drop that a subscriber, say N o. l, desires to communicate with another subscriber, pulls out switch-plug l, which will have the effect of including in No.' l circuit the central-attendants instruments and of closing the central battery-circuit- The central attendant then communicates with subscriber No.1 and learns that he desires to talk with, say, No. 3. The attendant thereupon pushes in plug l and pulls out plug 3 in the first row, in order to signal to No. 3, and having done so pulls out plug 3 in the first column. This will place subscribers l and 3 in communication with cach other, the central attendant being in the same circuit.l As soon as the attendant is sat isiied that subscribers l and 3 are talkin g with each other he will push in plug 3 in the iirst row, which leaves subscribers l and 3 in com.-

munication by means of plug No. 3 in the iirst column, the central-attendants circuit being cut out.

' Supposing that more than two subscribers, as Nos. 2, 4, and 5, should desire to communicate simultaneously with each other, this can be made possible by pulling out plugs l and 5 in column No. 2. It may also be done by pulling out plug 4t in column 2 and plug 5 in column t.

It will also readily be seen that all the subscribers can be put on the same circuit by pulling out plugs 2, 3, 4t, and 5 in column l.

The annunciator-drops for the different subscribers can be conveniently placed in the vacant triangular space in the right-hand lower corner of the switchboard, as shown in Fig. 3.

In case the number of subscribers is too large for a single switchboard a number of such switchboards can be used, slightly modified to connect them lwith each other. This is illustrated diagrammatically in Fig. 9, which shows five sections AX BK C'x DX EX, each of eight subscribers. These sections of a multi. ple switchboard differ from the single switchboard described above in that in the upper part of each, above the shelf or row of plugs for throwing in the central-attendants instruments, are four shelves precisely like the attendants shelf or row. Thus section Ax has the four rows By Cy Dy EY. Each row, as BY, and the connections and switch-plugs thereof, is precisely like the attendants row or shelf on the section AX, except that Vthe pair of wires corresponding to those which in .the central-attendants row go to the attendants instruments now go to the row marked AY on section BX. Similarly the wires from the row Cy go to the row AY on section C, and so on. Supposing then that subscriber No. G on section AX desires to communicate kwith subscriber No 3 on section DK, the attendant will first pull out plug 6 in row Dy in section AX, and will then himself or another attendant pull out plug 3 in row A' in section D". No. 6 in section Ax and No. 3 in section DX will then be in communication with each other.

Having thus fully described my invention, what I claim isl. In a switchboard, a series of loop-lines connected to pairs of terminals of subscribers wires', each loop-line comprising a number of pairs of contact-points, and bridges for said points, a pair of such points on one loop being arranged in proximity to a pair of such points on another loop, whereby, when said bridges are broken, and said contact-points are connected across from one loop to the other, said loops are brought into a single circuit, substantially as described.

2. In a switchboard, a series of loop-lines connected to the respective terminals of the subscribers lines, each loop-line comprising a number ofpairs of contact-points, one pair for each of the other loop-lines, and bridges for said points, each pair of such points hav- IOO IIO

ing in proximity thereto one of the pairs on another loop, whereby, when said bridges are broken, an d said contact-points are connected across from one loop to the other, said loops are brought into a single circuit, substantially as described. i

3. In a switchboard, a series ot loop-lines connected to pairs of terminals of subscribers lines, cach loop-line comprising a number of pairs of contact-points, and bridgesfor said points, a pair ofsuch points on one loop being in proximity to a pair of such points on another loop, in combination with a switch-plug which simultaneously breaks said bridges, and connects the contact-points on one loop with those on the other, whereby said loops are brought into a single circuit, substantially as described.

4. In a switchboard, a series of loop-lines connected to the respective terminals of the subscribers lines, each loop-line comprising a number of pairs of contact-points, one pair foreach of the other loop-lin es, and bridges for said points, each pair oi' such points having in proximity thereto one of the pairs on another loop, in combination with switches which simultaneousl y break said bridges and connect the contact-points on one loop with those on another, whereby said loops are brought into a single circuit, substantially as described.

5. In a switchboard, a series of loop-lines connected to the respective terminals of the subscribers lines, and forming normallyclosed circuits therewith, each loop-line comprising a number of pairs of contact-points, one pair for each of the other loop-lines, each pair of such points havingin proximity thereto one ot the pairs on another loop, in combination with switches, each switch, in its normal position, closing two pairs of contactpoints on different lines adjacent to each other, and, when operated, opening said pairs, and connecting the contact-points thereof across from one line to the other, substantially as described.

G. In a switchboard, a series of loop-lines connected to the respective terminals of the subscribers lines and forming normallyclosed circuits therewith, each loop-line comprising a series of normally-closed bridges adapt-ed to be broken for connecting with the lines of a higher number, followed by a series of similar bridges for connecting; with lines of a lower number, the two bridges on two loops for connecting the corresponding lines being placed in proximity to each other, substantially as described.

7. In a switchboard, in combination with the pair of spring-jacks, and the pair of contact-plates, either spring-jack and its correspondin g contact-plate being connected to the terminals of one of two subscribers lines, forming a broken loop between said terminals, the switch-plug having the upper and lower connected contact-plates normally contactin g with said jacks and corresponding contact-plates for simultaneously bridging said broken loops, and having upper and lower bridge-plates adapted to bridge, the one the spring-jacks, andthe other the contact-plates, when said switch-plug is operated, substantially as described.

8. In a switchboard, a series of loops conneeted to the pairs of terminals of the subscribers circuits, each loop having a series ol' bridges, each bridge being adjacent to a bridge on one of the other loops, and independent-ly-operated switches whereby any one, or more, or all of said other loops can be substituted for the bridge, adjacent thereto, on the single loop, and be brought into a singleV continuous circuit therewith, substantially as described.

9. In a switchboard, a series oi' loops connected to the pairs of terminals of the subscribers circuits, each loop having a bridge, a series of pairs of contacts, one adjacent to each bridge, two lines, :normally open, proceedin g to the central-attendants instruments, and passing through opposite contacts of the pairs, two other lines, normally open, to the battery-circuit of the central-attendants transmitter, and a switch for cach loop which simultaneously breaks the bridge and connects its ends to the contacts of the adjacent pair, thus throwing the central-attendants instruments into the subscribcrs line, and closes the battery-circuit, substantially as described.

10. A switchboard forming a section of a multiple switchboard, comprising a series of loops, one for each subseribers circuit of said section, each loop having therein a bridge for connecting with another section of the multiple switchboard, said bridges in the several loops having adjacent thereto pairs of contact-points, the opposite points of the pairs being connected by wires to the other switchboard of the section, and means for breaking any one of the bridges and connecting its ends with the adjacent contact-points whereby said loop is placed in communication with the other section of the switchboard, substantially as described.

ll. A section of a multiple switchboard having rows of switch-plugs, there being for each row a pair of open wires to one oi' the other sections, the switch-plugs of said rows forming columns, one column for each subscribers circuit of said section, the switchplugs of the same column normally forming bridges in the subseribers circuit of said column, any switch-plug on being moved from its normal position breaking the bridge and making contacts with the pair of open wires to the corresponding other section o'l' the multiple switchboard, substantially as described.

In witness whereof I have hereunto set my hand in the presence of two witnesses.

DAVID M. MUNRO. Witnesses:

FRANCIS M. WRIGHT, R. M. ELLIOTT.

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